The present invention relates to an image sensor and a sensor module. For example, the present invention relates to an image sensor and a sensor module which have a configuration in which the image sensor and an arithmetic unit that controls the image sensor are provided separately.
In recent years, the demand for widening the dynamic range of an image obtained by an image sensor has been increasing. An HDR (High Dynamic Range) technique is known as a technique for widening the dynamic range of an image. In the HDR technique, a high-brightness side image obtained with a short exposure time and a low-brightness side image obtained with a long exposure time are synthesized to thereby widen the dynamic range of the image. Techniques related to the HDR technique are disclosed in Japanese Unexamined Patent Application Publication No. 2006-311240 and the specification of U.S. Patent Application Publication No. 2011/0285737.
In Japanese Unexamined Patent Application Publication No. 2006-311240, two image signals obtained based on different exposure times in an imaging device are simultaneously read out, and the images are synthesized by a synthesizing circuit. In this case, in the synthesizing circuit disclosed in Japanese Unexamined Patent Application Publication No. 2006-311240, when the image signal having a greater exposure of the two image signals is saturated, the image signal having a lesser exposure that is read out from a pixel adjacent to a pixel from which the image signal having the greater exposure is read out is amplified. Further, in the synthesizing circuit disclosed in Japanese Unexamined Patent Application Publication No. 2006-311240, when the signal of the pixel having the greater exposure is not saturated, the synthesizing circuit uses this signal, and when the signal of the pixel having the greater exposure is saturated, the synthesizing circuit uses the amplified signal, and synthesizes the signals of the pixels so as to produce an image signal for forming an image.
The specification of U.S. Patent Application Publication No. 2011/0285737 discloses a technique in which, when short second exposure image data obtained with a short exposure time and long second exposure image data obtained with a long exposure time are synthesized, the same format as that for an image which requires no HDR processing is used as an output image format.